| 摘要 |
A platform comprising a planar member having a top face and a bottom face and at least one pivoting member approximately in the center of said top face or bottom face, such that when a pivoting member is placed on a surface a distance depending on the shape of the pivoting member is created between the planar member and the surface and the platform is unstable. Thus the unstable platform encourages a user to expend energy, and is quickly height adjustable by choosing which pivoting member is placed on the surface. |
